1. Field of the Invention
This invention concerns disposable diapers, incontinent briefs, and the like having at least one unitary waistshield and elastically expansible waistband.
2. Background Art
Infants (and other incontinents) wear disposable diapers to receive and contain urine, feces, and other fluids discharged from the body. Disposable diapers function both to contain the discharged materials and to isolate these materials from the body of the wearer and from the wearer's surroundings. Modern embodiments of disposable diapers frequently perform these tasks in a manner superior to that of traditional cloth diapers.
Disposable diapers normally comprise three elements: a fluid permeable topsheet designed to be placed next to the wearer's skin; a liquid impermeable backsheet which forms, in use, the outer surface of the diaper; and an absorbent element interposed between the topsheet and the backsheet.
The topsheet is frequently a hydrophobic non-woven fabric which is readily permeable to fluid. Its hydrophobicity tends to cause the surface in contact with the wearer's skin to be dry and protected from fluids absorbed within the absorbent element.
The absorbent element receives and retains fluids which pass through the topsheet. It normally comprises a batt of airlaid wood pulp fibers.
The backsheet functions to contain fluids within the absorbent element thereby protecting the wearer's outer garments and other surfaces from soiling by these fluids. Backsheets are commonly formed of liquid impermeable material such as polyethylene film.
Disposable diapers having many different basic designs are known to the art. For example, Duncan and Baker in U.S. Pat. No. Re. 26,152, issued Jan. 31, 1967, described and claim a disposable diaper which has achieved wide acceptance and commercial success. Buell, in U.S. Pat. No. 3,860,003, issued Jan. 14, 1975, described and claims another disposable diaper which, too, has achieved wide acceptance and commercial success. The diaper taught by Buell differs from that taught by Duncan and Baker in many respects, not the least of which is the provision in the Buell diaper of elasticized (or expansible) leg cuffs. Another embodiment of disposable diapers is described and claimed by Aziz and Blaney in European Patent Application No. 82200801.7, filed June 29, 1982. The Aziz and Blaney diaper also provides elasticized (or expansible) leg cuffs, but is of a somewhat different design than that described by Buell.
Mesek et al in U.S. Pat. No. 4,324,245, issued Apr. 13, 1982; Pieniak et al in U.S. Pat. No. 4,337,771, issued July 6, 1982; and Mesek et al in U.S. Pat. No. 4,352,355, issued Oct. 5, 1982 describe disposable diapers having elasticized cuffs and elasticized (or expansible) waistbands.
Kievit and Osterhage, in European Patent Application No. 83307177.2, published June 4, 1984 as publication No. 0112655, based on U.S. Patent Application Ser. No. 06/444,543, filed Nov. 26, 1983, describe disposable diapers with elastically expansible waistbands.
Buell, in European Patent Application No. 82200161.6, published Sept. 1, 1982 as publication No. 0059015, describes disposable diapers with waistshields. A waistshield is a liquid impermeable barrier member provided at the edge of the absorbent core in at least one of the waist regions of the diaper. It comprises an outward portion projecting from the edge of the absorbent core away from the center of the diaper and an inward portion interposed between the topsheet and the absorbent core. The waistshield serves to prevent liquid from escaping from the absorbent core through its waist edges.
Other concepts have also been proposed to prevent the liquid which migrates toward the perimeter of the diaper from wetting the wearer's undergarments. For example, U.S. Pat. No. 3,520,303 which issued to Endres on July 14, 1970, teaches a disposable diaper having a leak-preventing barrier at the ends to prevent leakage at the waist. The barrier is a strip of thin film which is affixed between the topsheet and the backsheet along a single line at the perimeter of the diaper. Endres et al., in U.S. Pat. No. 3,900,031 issued Aug. 19, 1975, also disclose a thin film at the edge of a diaper.
Strickland and Visscher in U.S. Pat. No. 4,253,461, issued on Mar. 3, 1981, describe and claim another form of disposable diaper sometimes referred to as an incontinent brief and intended to be worm by adults.
While the disposable diapers described above, particularly those described by Duncan and Baker, Buell, and Aziz and Blaney, and Kievit and Osterhage, function in an exemplary manner, improved disposable diapers are still sought.